Three-position, four-way selector valve



July 1, -1952 T. H. HOLZ-ER 2,601,990

THREE-POSITION, FOUR-WAY SELECTOR VALVE Filed Aug. 2, 1950 5Sheets-Sheet l 77/50/20P6 /OL .Z5/Q .-36 JNVENToR.

00 19 TTG/PNE Y Patented July 1, 1952 THREE-POSITION, FOUR-WAY SELECTORVALVE Theodore H. Holzer, Glendale, Calif., assignor to Saval Divisionof The William R. Whittaker Company, Ltd., Los Angeles, Calif., acorporation of California VApplication August 2, 1950, Serial No.177,180

This invention relates generally to fluid valves, and more particularlyto fluid valves operating on high pressure duid, as used in modernaircraft control systems, e. g., 3000 p. s. i.

The present invention is directed, in one principal aspect, to aselector or control valve of a type employing a ported valve elementequipped with a known type of spring actuated axially movable ring sealengaging a lapped surface of the ported valve element surrounding thehigh pressure entrance ports thereof. The ported valve element in thisgeneral type of valve has sometimes been constructed for rotation, andsometimes for linear translation. The ring seals, protected againstleakage around their outsides by synthetic rubber O-rings, verysuccessfully seal against leakage of fluid even at high pressures.However, the effort to `move these valves when using high pressurefluids becomes very considerable, and it is accordingly one object ofthe present invention to provide a selector valve of the type mentionedhaving an easily operable pilot valve for controlling the hydraulicfluidto move the main valve. Further objects include the provision of animproved pressure balanced pilot valve, and theprovision of a main valveso constructed and arranged and so equipped that it is easily andreadily operated by pilot-controlled hydraulic means.

'A Valves vof the type under consideration are commonly of the four-waytype, though modified forms may be of the three-way or two-way types.Four-way valves of this general typev may be employed, for example,where it is desired to direct the flow of high pressure hydraulic fluidfrom Aeither one of two engine driven hydraulic pumps to either one oftwo hydraulic systems in an airplane, 'or from a single pump or pressuresource to either end of a double acting cylinder or cylinders, while atthe same time permitting the vfluid from the other end ofthe cylinder toow through the valve into a. return line and back to the reservoir. f

N Itis a purpose and a featurefofthe present `invention that thepilotvalve be controllable by electrical solenoid actuation, and it is afeature vand characteristic of the valveof the presentinvention, invonepf its principal forms, that the valve will not dump system pressurein the -case of an electrical failure, as is the case with some valvesof the prior art. The main valve `element of the invention returns to acentral neu- LLtral, position in the event ofjeither electricalor`Jnydrellli: failure, and inone-preferred form o f :the invention, thehigh pressure fluid at such time 2 Claims. (C1. 277-20) 2 is out off andheld, while at the same time. the two work or cylinder ports are alsosealed off, so vthat the fluid is held in the two ends of the workcylinder. In another embodiment, the two ends of the work cylinder areconnected to the return line upon the main valve moving to neutralposition, which it will do upon either electrical or hydraulic failure.A choice is thus hadas to whether, upon electrical or hydraulic failure,the fluid in the work cylindenis retained or released. l

A further object is the provision of a pilot controlled selector valvewhich will operate,"not only at high pressure such as 3,000 p. s. i..but down to as low as say 240 p. s. i., so that the valve remainsoperable even with considerable failure of hydraulic pressure.

A still further object is the provision of a pilot operated selectorvalve which is operable between the control positions in an extremelyshort interval of time, as for instance, within 'le of a second or less.

A further object is the provision of a valve of the general charactermentioned, having a simple and straight-forward design throughout bothpilot and main valve units, assuring satisfactory operation land longlife, as well as having the fea- V tures of compactness, quick, positive.positioning of both pilot and main valve, giving very sensitive controlof the power cylinder, and ease of installation in a'hydraulic controlsystem. Y

The main valve unit in a present preferred embodiment employs a portedslide type of valve. equipped with axially movable spring pressed ringseals engaging lappedsurfaces surroundingY the ports in the slidemember. This slide member is of rectangular cross-section, and isaccurately and closely fitted inside a broached passageway of similarcross-section in the valve body. Positioning of the valve is directlycontrolled by means of Afloating pistons engaging opposite ends of theslide valve .and which reactk to pilot controlled hydraulic pressure formovement to either selected position or to a neutral position determinedby centering springs acting on the saidv pis- 'tons and taking overcontrol when the pilo't conl to the V.floating work pistons at thetwo.ends of the main slide valve. Thisl `spherical poppet valveelementise'als at either of two seats which lare .situated to); allow aVpoppetp stroke of the order of .020 to admit fluid under pressure or toallow the pressurized fluid to escape. Each pilot valve, in the normal(solenoid de-energized), is spring-loaded against its pressure seat,with the opposite seat open for venting work piston; pressure chambersto the main valve return port. When either solenoid is energized, thecorresponding spherical poppet instantly seals the return flow seat andadmits liuid pressure to the corresponding work piston, causing the mainslide valve to move to the selected position. This slide valve movementalso compresses the springs at the opposite end so that when thesolenoid is deenergized, the slide valve automatically returns toneutral.

The pilot valve of the invention also has utility employed as the mainvalve component in certain types of cut-oit and three-way valves, aswill be described in the course of the body ci the specification.

lThe invention wili be more fuily understood by no w referringto thefollowing detailed description of certain present preferred embodimentsthereof, reference for this purpose being had to the accompanyingdrawings, in which:

Y Figure l is a vertical longitudinal section ci one presentillustrative four-way embodiment of thek valve of the invention, takenin accordance with the section line I-l of Figure 3, the main valvevbeing shown in neutral position;

Figure 2 is a view taken as indicated by broken line 2-2 of Figure l;

Figure 3' is a section taken on line 3--3 of Figure l;

Figure 4 is a section taken on lined-l of Figure l;

Figure 5 is an enlarged fragmentary view taken from Figure 1;

Figure 6 is an enlarged fragmentary view taken from Figure 3; and

VvFigure 7 is a fragmentary detail View taken from Figure 1, but showinga modiiied porting arrangement for the main slide valve. The inventionvwill first be described as ernbodied in a four-way, three-position,pilot conti'olled selector valve-whose main valve element is vof alinear travelling slide type. It may7 be assumed for illustrativepurposes that the valve will have four external pipe connections, one tothe high pressure'fluid source, two to opposite ends oi a work cylinder,and a fourth to a return line leading to a iiuid reservoir. Thisillustrative valve is shown in Figures 1-6, inclusive, to whichreference is first directed.

In said Figures 1-6, number I0 designates generally a valve body, whichincludes a generally rectangular central body block portion Illa andaxially alined tubular boss portions |01; projecting oppositely frombody portion Ia. The latter are here shown as provided with integralwall-engaging mounting brackets l, suitably perforated for mountingscrews. The top and bottom of central body portion Ia are formed withflat horizontal surfaces I2 and I3, respectively, and a hydraulicconnector fitting Ill, hereinafter more particularly described, issecuredagainst bottom surface i3, as by screws I3a, while a tapped borel5 sunk intoto'p surface I2 receives connector iitting l0. The latterhas externally threaded wall l1 adapted for reception in threaded boreI5, and a hex head `I8 at its outer end by which it is 'turned intoposition, and which ultimately shouldersgagainst body surface I2 as apositioning sto'p'v Fitting 'I6 is tapped as "at `-I9 to receive'conventional' guideway 26 for a main slide valve 21, formed of hardenedsteel, and having a corresponding square or rectangular cross-section.The guideway 2S is "precision formed, preferably by breaching, and theValve 21 is precision machined and ground to fit the guideway 2B withvery close tolerance, only sumcient working clearance being permitted toenable the necessary free sliding movement in the opera-tion of thevalve. The total clearance is of the order of .0005" to .001". The topand bottom surfaces of this valve member 2 are in addition lapped to anoptically iiat nish. Extending through the central body portion of thevalve between annular shoulders 2l are semi-rounded grooves 2Q and 304(Figure 4), one on each of the slide valve 21. The grooves 29 and 39are sunk into the otherwise at side wails of the rectangular guideway26, and they extend through the central bodyL portion of the valve andopen at their jends through the vtwo annular shoulders 2l. The slidevalve 21, as will be seen in Figure 1, is of somewhat greater lengththan the distance between the two shoulders 2 I, so as to have anoperative range of movement in either direction from the neutralcentralized position illustrated in Figure l. The limit of movement ineither direction from the centered neutral position of Figure 1 is ofcourse reached when the end of the slide valve reaches the correspondingshoulder 2 l.

Slidably itted in bores 20 in baci: of the two ends of the slide Valve2;'1 are freely floating pistons 35, each formed with a peripheralgroove in which is seateda synthetic rubber O-ring 31 and a back-up orpacking ring 33.

Outside of or in back of each of the pistons 3 is a tubular spring seator retainer 40, the latter being freely receivable inside the bore 20and having at its outer end an external annular positioning ange 4islidably receivable inside the counterbore 22 and engageable against theannular shoulders 23. This spring retainer 40 has an inner end wall 42,forming a pocket for reception of the inner end of an outside coilcentering spring 43, while a small tubular boss 44 projecting rearwardlyfrom wall 42 forms a positioning means for an inside coil 'centeringspring l5- A passageway 46 extending through the centerof wall d2 andthrough boss 44 permits passage of hydraulic'pressure fluid'iromthechamber 41 inside bore 22 to the piston'S. y

The chambers 4l' are closed at their outer ends by caps 50 securedl tothe tubular body members I0b as by screws'l; c'AIhe'se caps i0 haveannular shoulders 52 which engage Vthe endsof the `tubular body portionsith," and have tubular `'projections 53 snugly received insideithe'boresV22, the latter being provided ,with external annular 'groovestted' withO-rings 55 to seal against leakage to the outside from the pressurechamber 41. `The rearward wall 56 "of each ofthe caps '50 affords a seatfor lthe coil springs Y'i3-'and '45, and a central boss5l centers theinside spring 45, while `theinterna-l-'bore of the cap-is `such vas'toaccomodate and f center the larger voutside spring 443. To prevent theturns of the small inside spring 45 .from working in between the turnsof the large outside spring 43, the two springs preferably have oppositepitch, as clearly illustrated in the drawings. The purpose of having thetwo springs, one inside the other, is Asimply to secure suiiicientspring pressure and range of action within the space accommodation ofthe present design.

The main slide valve member 21 of the present valve is formed with apair of longitudinally spaced, symmetrically located, oppositelyinclined fluid bores 60 extending between its top and bottom faces,these bores inclining outwardly ory away from one another in a downwarddirection. Valve member 21 also has a centrally located horizontal bore6| extending between the two side surfaces thereof, and communicating atopposite ends with the two grooves 29 and 30 (Figure 4). A central bore62 extends downwardly from bore 6| through the bottom surface of thevalve 21.

The previously mentioned tapped bore I 5 sunk into the top side of thevalve body terminates at an annular shoulder 10, and extendingdownwardly from the latter is a reduced bore 1|, the latter terminatingat annular upwardly facing shoulder 12. Extending downwardly throughthis shoulder 12 is further reduced bore 13 which opens into the top ofthe guideway 2S for slide valve 21. Slidably received in the bore 13 andserving as a port for the hydraulic fluid is a shear seal ring 14 ofhardened steel, externally cylindrical, having a narrow annular seatingsurface 15 at its lower end for engagement withthe upper lap finishedsurface of slide valve 21, and having a wider seating surface 16 at itsupper end. The lower seating surface 15 is ground and lapped to anabsolutely fiat surface. The opening at the lower end of this shear seal14 is sufficient to accommodate the bores 60 of the slide valve whenregistered therewith. That is to say, when a given bore 60 is registeredwith the shear seal 14, the seating surface 15 of the shear seal willengage the upper surface of the slide Avalve all around the periphery ofthe bore 60, so as to accomplish the necessary seal.

The shear seal ring 14 is pressed downwardly into sealing engagementwith the slide valve 21 by a coil spring 80 bearing on the upper end ofthe shear seal and confined within a sleeved member 8| located in bore1|. The inner end of fitting I 5 engages the outer end of sleeve 8| andextends inwardly therefrom to afford an overhangi'ng shoulder 82 againstwhich the upper end of lthespring 80 may bear. The shear seal ring isalso pressed down against the valve 21 under hydraulic pres-v sure,since its exposed upwardly facing area is greater than its exposeddownwardly facing area. Located in the space between the lower end ofsleeve member -8I and the shoulder 12 are an O-ring seal 85 and aback-up ring 86. Fitting I6 includes wall portion 81 formed with uidports 88, permitting the high pressure hydraulic iiuid introducedthrough'the fitting I6 to be not only passed downwardly Va sleeve member8 I to and through the shear seal ring 14 to the ported main valvemember 21, but also to pass through the ports 88 into the chamber 90immediatelyv above the shoulder 10, and this pressure fluidsoV Yintroduced to the chamber 90 is utilized as presently to be describedfor the control-of the pilot valves. t A

- It 'willbe seen that withthe slide-valveZl in the neutralspring-centered position shown in 10 fore in communication with thehydraulic pressure fluid introduced through the inlet fitting I6.

At such time, the lower end of such port 60 will register andcommunicate with a sealed bore |00 `extending downwardly through thevalve body to the lower body surface I3. There thebores |00 communicatewith ports I 0| in fitting I4 opening into tapped tubular bosses |02adapted to receive coupling means to the fluid pipes leading to ythe twoopposite ends of a work cylinder. The bores |00 open to guideway 26through reduced bores |03, in which are slidably received shear sealrings |04, exactlysimilarto the previ'usly described shear seal rings15,v and these shear seal rings |04 are pressed into sealing engagementwith the bottom surface of valve 21 by coil springs I 05 bearing ontheir lower ends and seated at the bottom on the coupling member I4, asshown. The coil springs |05 are confined inside sleeve members litt`placed inside bores |00 and arranged'in overlapping relation with thelower ends of the shear seal rings, rubber O-ring seals and packingringsA being-placed around the shear seal rings |04, exactly as with thepreviously described shear seal 14. Rubber O-ring seals I0 are alsoplaced in grooves or counterbores sunk into valve body surface |3 aroundthe bores |00 for protection against leakage at that point.

It will be seen that when the upper end of one of the ports `(S0 isregistered with upper seal ring 14, with its lower end then registeredwith one of the lower seal rings |04, the port 62 in slide valve 21 willthen be registered with the other of the lower seal rings |04. Hence,hydraulic iiuid fromthe pressure source will at such time enter viaupper fitting I6, pass through shear seal ring 14, thence downwardlythrough the registered port 60 to one of the lower shear seal rings |04,and on downwardly via the latter .to and out through the correspondingcoupling boss |02 to oneend of the work cylinder. At the same time.fluid from the other end of the work cylinder will be returned via theother coupling boss |02 and will be passed upwardly through thecorresponding shear seal ring |04 to slide valve port 62, then be inregister with the last-mentioned seal ringv |04. Thisvreturn fluid isconducted from port 62 through transverse valve port 0| to channel 30(Figure 4) whence it is received by a passage leading downwardly fromchannel 3,0Y through the Vvalve body to. vcommunicate with a passageway|2| in coupling vmember I4, passage |2| opening into tapped tubular boss|22 i-nto which the return or exhaust fiuid pipe is understood to becoupled. For the purpose of sealing seal V|23 is placed in acountersinkv |24 in the valve body aroundpassage |20, and this O`ringispreferably centered by forming an annular 76 ridge |25 on the couplinglmember |14 around-passagel'20. 1 Working in suitable guides mounted itral block portion site sides'of inlet fitting I6, aretwo'parall-elpilot n the cenbetween passages |20 and' I 2|, a rubber Gering 0a of thevalve body, on oppo- Lvalve plungers l |30, each comprising 2a @centraltspherical npoppet.y valve.y head v13|, .reduced stems,

7 132L andl 133 extending in opposite directions from the head 131, andcylindrical plunger parts 134 and 135 on the -ends of stems 132 and 133,respectively, the plunger parts 131i and 135 being of slightly lessdiameter than the spherical head 131. To provide for accommodation ofthe guides, seats and seals for these plunger-s, the valve body blocklea is formed with a bore 141i extending inwardly from its dat irontside 141, a reduced intermediate bore 142. extending inwardly from bore1&1), and a further reduced inside bore M3 extending inwardly from boreM2. The body is counterbored from the other side to form bore 115s ofthe same diameter as bore 1132 extending inwardly to `a juncture withbore 1153.

Plungers 1311 :and 135 are slidably mounted in suitably bored glands1511 and 151, respectively, located in bores 142 and 144,respectively.The plungers 131B and 135 are also slidably 'tted in tubular portions152 and 153 of valve seat members 154 and 155, respectively. The seatmember 154 has an inner cylindrical head portion 156 fitted inside bore143, and peripherally grooved to receive an ordinary O-ring seal andback up ring, as illustrated. At its other end, the member 151i has anenlarged annular flange 1S@ received snugly within bore 1132. The bore152@ of tubular member 152 is just slightly less than the diameter ofspherical poppet valve 131, and the Ainner end of saidbore confrontspoppet valve 131 as indicated. Seat member 155 is a substantialdup-licate of member 154, its tubular po-rtion 153 having at the innerend a cylindrical head 161 fitted with an O-ring and back up ring thesame as in the case of the head 15s of seal member 154, and the outerend of the member 153 carries annular vilange V1152 seated in bore 144.The bore 153e!I of tubular member 153 is slightly less in diameter thanthe diameter of spherical valve element 131, and confronts the latter inopposition to the bore 152er. It will be seen that the intersection ofthese bores 152e and la with the 'flat ends oatv the cylindrical heads1-55 and 1&2 forms round, sharp seats s and s', respectively, forseating engagement with the spherical poppet valve element 131. The headi451 of seat member 155 has projecting spacer :lingers 15P. (see Figure5) which engage the head 15e of seat member 151i and space the two valveseats s and s apart `for a pilot valve stroke of approximately .020.

The aforementioned glands 150 and 151 back up and engage thecorresponding flanges 1611 and 152 of the seat members. yGland 15B isconnned by a shim 135 seated in bore M2, and gland 151 .V-

source pressure fluid space Si) (seeFigure 1) to Van annular space 1'11formed at the kjunction of bores 142 and 143, between the head of seatmember V151i, and Yits flange 151%. lCommunication '1s establishedbetween space 1'1'1 and the interior of tubular member 152 by means ofports 12. Vr'Pressure fluid thus passes through bore 1li), chamber 111.,,ports 132 Vand the space inside oi tubular `members 152 vand aroundvalve stem 1512v tol Ithe-poppetvalve 1,31. The same l'pressure plunger160, so that the pressures are balanced and there is'no net force .fromfluid pressure in either .direction in the -static condition with thepoppet valve on its seat s. The poppet valve is normally maintained insealing engagement with its seat s `by means of a coil spring 1'15surrounding plunger 134 and ccm'ned between the outer end of gland 142and a retaining ring 111 mounted on plunger 134 near its outer end.

Actuation of the pilot valve is, accomplished by pressing inwardly onthe outer extremity of plunger portion 134 to move the plunger and itspoppet valve 131 throughthe .020" stroke necessary to unseat the poppetvalve from its .seat s Yand to `seat the same on the alternate seat s.This lcan be accomplished manually, but is preferably accomplished by asuitable solenoid. A solenoid is conventionally indicated at v18S),beingr shown `to have a plunger 1'31 understood to be .advanced intooperative engagement with plunger 13S when the solenoid is energized. Itwill be understood that upon de-energization of the solenoid, itsplunger 181 will retract and release the pilot valve plunger 131) forreturn under the influence of its'spring HI8. To provide for manualactuation even when having the solenoid installation, the `solenoid mayhave an extending push button device suchV as indicated at 132. The twosolenoids for thetwo pilot valves may behoused in a suitable casing,understood to be secured properly to the face 141 of the valve body. Thesolenoids are shown to have tubular Ibosses 181m screwed into tappedbore his. These valve operating solenoid devices form no part vof thepresent invention, and are hence only conventionally shown herein. Itwill be understood, however, that in connection 'with the two sclenoids,an electric Vpower circuit will be provided and also a three-positionswitch providing for 4energization of either solenoid (but not bothtogether) ,and for de-energization of both together. it will of coursealso be understood that any suitable alternative means may be adoptedfor operation Vof the pilot valve plungers V139, as required to meetvarious conditions.

Depression of the ,pilot valve 13B against its spring 175 in the mannerindicated above results, as described, in unseating the poppet valve 131from seat s and moving it to the opposed seat s. This allows pressureduid to escape from the bore of tubular member 152 past the poppetvalve, whence it may'ow outwardly between spacer fingers 1&4 to a fluidpassageway 185 leading to -the previously `described hydraulic pressurefluid chamber dl (see Figure 1).

As earlier described, in the abs-ence of actuating forces, themainfslide valve 2l is held in a centralized position between the 'twocentering springs. Presence of hydraulic pressure fluid in a chamber ilthrough actuation of the pilot valve `as just described results inapplication of pressure fluid against oating piston 31, the fluidreaching the latter through the port 46 in the -spring seat member tu.rhe floating piston 31 vaccordingly advances, pushing slide valve member21 ahead of it against the opposed centering,r spring, until'the piston31 reaches the stop shoulder 21, at which position the slide valvemember 2l has moved one of its fluid ports 60 into a positionestablishing pressure fluid communication between the Vring seal 'l5 anda lower ring seal 1&4. At the same time, as earlier described, thereturn port 62 of the main valve registers with the other lower ring.seal104. Thus it will be,

-95 seen that actuation of pilot valve plunger e |30 sendspressure uidfrom inlet tting vi6 past pilotpoppet valve |3| and into chamber 41,from which itexerts pressure through floating piston 36 on the end ofthe main slide valve to move the same into a position where pressurefluid from the inlet fitting can travel down through a main valve port50 kto one or the other of the tapped pipe coupling bosses |02. Pressureiiuid is thus delivered to4 one of the pipes connected to a tubularcoupling boss |02, while at the same time return fluid will enter viathe other coupling boss |02, and will be delivered via port 52, port 6|,and passages |20 and |2| to the return pipe coupled into the boss |22(Figure 4). The main slide valve will of course be moved in onedirection or the other, depending upon which of the pilot valve plungers|30 has been actuated.

When the pilot valve plunger |30 is released, it returns under theinuence of its spring |16 through its .020" stroke, poppet valve |3|separating from seat s and again making sealing env gagement withpressure fluid seat s. Main slide valve 2'| will then be returned to itsneutral center position by the previously compressed centering spring,thereby cutting off the pressure uid at ring seal 14, and hydraulicfluid will be exhausted from chamber 41 through passage |85, and willflow past seat s into the annular space between tubular member |53 andpilot valve stem |33. This fluid then flows through ports |90 in tubularmember |53 just inside flange ISI, to be received by a passage |9|extending downwardly and opening into groove 29 (Figure 4), whence itmay travel along groove 29 to and into transverse slide valve port 6|,to escape via passages |20 and |2| leading to return It may be notedthat the grooves or channels 29 and 30 establish communication betweenthe inner ends of the two bores 20, permitting fluid flow back and forthbetween these spaces to enable the movement of the pistons 36.

One particular feature of the main valve is the fact that the slidevalve 27, with its close precision fit in the guideway, is actuated bybut not rigid with, the floating pistons 36. This assures proper workingof both slide valve and pistons, even though there be a littlemisalinement of the piston bores relative to the guideway for the mainvalve.

Attention is called to the fact that upon electrical failure, both pilotvalves must necessarily occupy their neutral positions, and the mainvalve must return to centered position, cutting off the flow of sourcepressure fluid, and cutting off communication to both ends of the workcylinder. No hydraulic fluid is hence dumped as a result of electricalfailure. However, since the solenoid plungers can be manually actuated,the system remains fully operative under manual instead of electricalcontrol.

In the event of hydraulic source pressure fluid failure, the system bothpilot and main valves, will return to neutral, the same as withelectrical failure. However, while the system is designed for 3,000 p.s. i., the valve remains operative down to about 240 p. s. i.

It will be evident that the valve has the important feature ofnon-interflow between partially open ports in intermediate positions ofthe main slide valve. In other words, there are no intermediatepositions of the slide valve at which hydraulic uid can nd an unintendedpath of communication between two valve ports.

Figure 7 shows a modified porting arrangement for the main slide valvev2T of Figure 1. Here, there are two slanting ports 200, placed insideand substantially parallelto ports 60, positioned to establishcommunication between shear seal rings |04 and transverse slide valvebore 6| in the neutral positionv of the valve. Accordingly, in thismodification, fluid is freeto'escape to return from both ends of thework cylinder when the main valve is in neutral position. Y f

A further modication, unnecessary to illustrate, consists in using amain valve positioning spring at only one end of the slide valve, and afloating piston and pilot controlled means for applying pressure fluidthereto at only the other end of the slide valve. In neutral position,then, the slide valve is moved its ,full stroke in one direction by thepositioning spring, and when the pilot valve is actuated, pressure uidVis delivered to the floating piston to move the slide valve against thespring in the opposite direction. The porting of the main slide valveand of the valve body may follow, in effect, vthe arrangements suggestedin Figures 1 and, '7, or may be as desired. y I Also, the pilot valve ofthe invention may be used independently as a shut-off valve, eithernormally open, or normally closed. The pilot valve as shown in Figures 1and 6 illustrates typically the use as a normally closed shut-off valve,since actuation of the plunger |30 against the influence of thepositioning spring |16 results in displacing the spherical poppet valve|3| from its seat s, causing flow to take place past the valve |3| tobel received by the passage |65.

Also, the use of the pilot valve as a normally open shut-01T valve isillustrated in Figures 1 and 6, when the return flow from the pistonchamber 4'! through passage |85 to the interior of seat member |55 istaken into consideration. There, the fluid is owing past the sphericalpoppet valve |3| (then seated on seat s) into the bore of seat member|55, to be exhausted through ports on its way to returnf If the valveactuating solenoid is energized, the spherical poppet |3| seats at s',shutting off any such iiow into the bore of seat member |55. It shouldbe evident how such a valve device may be employed as a iiuid shut on"valve in many sitnations.

It is lof course to be realized that many modifications in design,structure and arrangement may be madein the valve without departing fromthe spirit of the present invention, andr without departing from thescope of the appended claims.

I claim:

l. In a fluid valve, the combination of: a valve body, a hardened slidevalve of rectangular crosssection, a guideway of correspondingrectangular cross-section, formed in said valve body and slidablyreceiving said slide valve with a close sliding t, opposite faces ofsaid slide valve having a precision nish, spring means for centeringsaid slide valve in a neutral position in said guideway, pressure fluidmeans for moving said slide valve through a predetermined stroke ineither direction against said spring means, a guide bore in said valvebody opening into one side of said guideway to face one of said finishedsurfaces on said slide valve, a pair of guide bores insaid valve bodyopening into the opposite side of said guideway to face the oppositefinished surface on said slide valve, said pair of bores being spacedapart longitudinally or said guideway by a distance equal to twice thestroke of the slide valve in either direction from neutral position,external uid openings in said body communicating with said bores,hardened sealing rings in said guide bores pressurally engaging saidiinished surfaces of said slide valve, a pair of ports through saidslide valve extending between said finished surfaces thereof, said slidevalve ports opening through said one of said v:finished surfaces onopposite sides of the rst mentioned guide bore and at spacing distancestherefrom equal to the stroke of the slide Valve in either directionfrom neutral position, said slide valve ports opening through saidopposite finished surface of said slide valve outside said pair of guidebores by center-to-center distances equal to said stroke of said slidevalve, a fluid discharge passage in said slide valve opening at one endthrough said opposite finished surface on said slide valve at a pointhalf way between said pair of guide bores, and opening at its other endthrough a side of said slide valve between said iinished surfaces, alongitudinal groove in the Wall of said guideway opposite said other endof said passage to receive uid therefrom, and a discharge passage insaid valve body leading from said groove.

2. The combination of claim 1, in which the slide valve has anadditional pair of fluid ports located inside said first mentioned slidevalve ports, said additional fluid ports opening through said oppositeiinished surface of said slide valve in positions to register with saidpair of ring seals when the slide valve is in neutral position, and theother ends of said ports communicating with said longitudinal grooveleading to said fluid discharge passage in the valve body.

THEODORE H. HOLZER.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Rode Oct. 8, 1946

